I have a question well I put regular gas in my jaguar because they had the gas pumps backwards and I did not pay attention so I had to get on the high way and I want to know if this can mess up my car but after I got home I put the premium gas can it mess it up and I read about it can make the car a knocking sound and if it does can it go away to put the premium gas in it

 

It's very unlikely there is any damage, because all modern engines have knock detectors and will retard the ignition to eliminate it. If the system could not retard the ignition enough to eliminate it, it would have displayed a fault message. US gas (UK-petrol) tends to have lower octane ratings than here in Europe and the engines are set up to handle that. Do you know the octane rating of the regular gas you put in ? Europe we have so-called "Premium", (there is no "Regular), at 95 RON, and higher octane fuels around 99 RON. If you know the US octane rating, just convert it to RON on the internet and compare.

 

It will be OK.

At least it wasn't diesel.

 

The only difference you may notice is a slight decrease in gas mileage. Motor output will decrease but you probably won't notice it.